There is little commercially available control and power hardware for undersea applications. Therefore, most applications require adaption of presently existing hardware which requires sea proofing and sometimes major modifications. Most common undersea working hardware is probably electrical in nature and is prone to corrosion, electrolytic action, current leakage, and insulation and coupling problems. When this hardware is combined with mechanical jacks, winches, gear boxes, and so forth, the problems magnify because of the interfacial leakage paths, and mechanical stresses.
Pneumatic equipment is available to some degree, but even with more limited selection than electrical equipment. Pneumatic equipment is handicapped by the energy storage problem (compressed air), and also leaves a signature in the form of air bubbles. As operational depth increases, efficiency decreases.
Hydraulic equipment has the most attractive features for underwater use, however, very little of this equipment is available. The use of standard surface-hydraulic equipment in an underwater environment creates immense corrosion problems and is difficult to control with standard or modified electrical, mechanical, or pneumatic control equipment.